'El Niño's' impact on Indonesia

DW: Weather forecasters from the US, Australia and Japan are predicting a El Niño-related weather event in 2015. How likely is this?

Robert Field: There is already an El Niño. We have seen such conditions for at least a month. The most recent projections suggest that there is a 90 percent chance that they will last through the remainder of 2015, and possibly into the spring of 2016. Less clear is how strong it will be. Not all El Niños are created equal. There are indications that this El Niño will be among the stronger ones.

Can you briefly explain what El Niño is?

El Niño is a change in ocean and atmosphere patterns in the Pacific. Ocean and sea surface temperatures under El Niño conditions are warmer than usual in the Eastern Pacific, causing changes to the tropical rainfall belts. In Indonesia's case, the warmer sea surface temperatures cause the rainfall to shift.

Indonesia is normally one of the rainiest places in the world. But the sea-surface temperature changes draw the rain away from the maritime continent. It moves eastward over the western Pacific Ocean.

What does El Niño mean for Southeast Asia?

El Niño generally causes drier conditions over Southeast Asia and Australia, and the effects vary with the seasons. During the boreal summer and fall, Indonesia has drier and longer dry seasons.

There is a circulation over the Pacific Ocean and Indonesia is right at the terminal end of that. Because of that the country, along with northern Australia, is most sensible to any changes to these patterns. And you can see those effects as you move further away, say, into the Mekong region and even into India - but they are most pronounced over Indonesia. In Asia, the further away you move from the equatorial Pacific Ocean the weaker the impact.

In 1997/98 there was a very strong El Niño. During that period large fires destroyed thousands of hectares of forest in Indonesia. Does this year's El Niño endanger Indonesia's forest?

The 1997 El Niño was the strongest in a hundred years and that was reflected in these destructive fires. Whether or not the phenomenon approaches the same level this year is hard to say. That really depends on what happens over the next few months and whether or not the current El Niño conditions become stronger.

The main cause of the fires, the haze and the smoke is the burning of peat or underground organic matter. Fires lit on the surface in order to, say, clear agricultural or logging debris, also affect the underground when the peat becomes too dry. There its burns continuously. The drought is not yet extreme, but conditions in central Sumatra have now transitioned into a situation where this peat is dry enough to burn.

If you have a look at the satellite fire detection map you can see that the situation started deteriorating just recently as conditions got dryer. It shows that there are insufficient prevention activities on the ground. Stopping these fires is all about prevention. They are nearly impossible to put out once they get underground.

It is important to reiterate that all fires in Indonesia are man-made and happen for two reasons: They occur because it is drier than during a normal dry season and also because of the degree of human activity on the landscape.

Malaysia and Singapore have been massively affected by the haze. Do you think that local governments are better prepared to prevent the fires?

There is no indication that they are. A positive step in September 2014 was Indonesia's ratification of the transboundary ASEAN Haze Agreement which was initiated in 2002. This includes prevention measures, but this year will be the test of whether this translates into meaningful action on the ground.

It should be pointed out that there are broader socio-economic factors to consider surrounding Indonesia's land use. What's ultimately driving the fires is the demand elsewhere for products derived from crops such as oil palm.

Do those fires have an impact on the regional climate?

The fires produce an enormous and completely disproportionate amount of smoke given the size of the burning region, and, more generally, the size of Indonesia's economy. An analysis of the 1997 fires made a conservative estimate that the emissions from those fires where equivalent to 13 percent of total fossil fuel emissions during the whole year.

Severe burning doesn't happen every year, but often enough to make Indonesia a disproportionate contributor to greenhouse gas emissions. Smoke from the fires also degrades the air quality in Indonesia and its neighbors. One of the worst effects of the fires is on respiratory health.

There is more research needed on what the regional climate effects are in detail. You can imagine that all that smoke will block sunlight from hitting the ground and that the darkness of that smoke will absorb sunlight. This changes the temperature structure of the atmosphere, possibly affecting weather patterns and rainfall. However this is an area of active research.

Robert Field is a Columbia University Associate Research Scientist at the NASA Goddard Institute for Space Studies in New York. He specializes in climate modeling, stable water isotopes, paleoclimatology and biomass burning.

The interview was conducted by Rodion Ebbighausen.